Linked tread apparatus for improved performance on loose surfaces

ABSTRACT

A tread link assembly is provided for improving the performance of a wheel on loose surfaces. The tread assembly includes a plurality of linked plates forming a circuit around the outer circumference of the wheel. The linked plates include first and second linking structures and releasable fasteners for linking adjacent plates together. The together the plates create a tread surface that is wider than the axial width of the wheel.

BACKGROUND

The present invention relates to an apparatus that may be mounted to oneor more wheels of a personal conveyance vehicle such as a baby stroller,a wheel chair, cart, or the like. The apparatus provides a wider treadsurface to the wheel for improving the wheel's performance rolling overloose surfaces such as sand, snow or mud.

Personal conveyances, such as baby strollers, wheel chairs, rollingcarts, and the like generally have narrow wheels. Narrow wheels allowsuch devices to roll more efficiently over hard surface such asconcrete, asphalt, wood flooring and the like. Narrow wheels can be adetriment, however; when traveling over soft, loose surfaces such assand, snow or mud. When such surfaces are encountered, narrow wheelstend to sink into the loose material, making progress over such surfacesdifficult if not impossible. This situation can cause many popularplaces such as sandy beaches, snow covered parking lots, nature trailsand others inaccessible to such vehicles.

A solution is needed to make such places more accessible. Preferably asolution will be provided for adapting existing personal conveyances andother vehicles to allow them to travel easily over surfaces on whichthey presently do not perform well.

SUMMARY OF THE INVENTION

An embodiment of the invention provides a removable tread assembly thatis adapted to be installed around the outer circumference of one or morewheels of personal conveyance vehicle such as a baby stroller or a wheelchair. The assembly is formed of a plurality of substantially identicaltread links. The tread links include a generally flat tread plate havingan upper/outer surface and a lower/inner surface. The upper/outersurface forms a tread surface to engage whatever surface the wheelhappens to be rolling over. The tread plates have a width greater thanthe axial width of the wheel, providing a greater surface area forengaging loose surfaces such as sand or snow. The tread plates have afirst end and a second end. A first linking structure is formed adjacentto the first end of the tread plate and a second linking structureformed adjacent the second end of the tread plate, such that the firstlinking structure of a first tread link is adapted to engage and besecured to the second linking structure of a second tread link. Aplurality of substantially identical link fasteners are provided toretractably engage the first and second linking structures of adjacenttread links to secure the adjacent tread links in an articulating mannersuch that the plurality of tread links may be linked end-to-end in acircuit around the outer circumference of the wheel. The tread links mayfurther include an inner side plate and an outer side plate dependingfrom the lower/inner surface of the tread plate. A portion of the innerand outer side plates may extend beyond the first end of the treadplate. According to an embodiment, the first linking structure includesa first pair of link pin apertures defined by a portion of the inner andouter side plates that extend beyond the first end of the tread plate.The second linking structure includes a second pair of link pinapertures defined by the inner and outer side plates in a recessed areaadjacent the second end of the tread plate. According to the embodiment,link pins are inserted into the first and second pairs of link pinapertures of adjacent tread links to secure the tread links together.

Another embodiment relates to a tread link that may be included in atread assembly for improving the performance of a wheeled vehicle onloose surfaces. According the embodiment a tread link includes a treadplate having first and second surfaces. A first linking structure isassociated with a first end of the tread link and a second linkingstructure is associated with a second end of the tread link. An innerside plate and an outer side plate depend from the second surface of thetread plate and extend between the first and second ends the tread link.The inner and outer side plates are spaced apart a distance sufficientto receive a portion of an outer circumference of a wheel onto which thetread link is to be mounted. A link fastener is provided which isadapted to engage both the first linking structure associated with thefirst end of the tread link and a second linking structure associatedwith a second end of a similarly constructed tread link. According to anembodiment, the first linking structure forms a protrusion extendingbeyond the first end of the tread plate. The second linking structure isformed within a recess defined by the second end of the tread plate. Theprotrusion is configured to fit into a corresponding recess of thesimilarly constructed tread link. The inner and outer side platesdepending from the second surface of the tread plate line the first andsecond sides of the protrusion as well as first and second sides of therecess. The inner and outer side plates define a first pair of link pinapertures adjacent the protrusion and a second pair of link pinapertures adjacent the recess. A link fastener including a link pin isinsertable into one of the first and second pairs of link pin aperturesand the other of a first and second pair of link pin aperturesassociated with the similarly constructed tread link to secure the treadlinks together. According to an embodiment, the fastener may be in theform of a U-shaped member having first and second deflectable arms, anda link pin defined by a pair of outwardly facing posts formed on theends of the first and second arms.

Still another embodiment provides an apparatus for improving a wheel'sperformance on loose surfaces. The apparatus is formed of a plurality oflinked plates. Each linked plate has an upper surface, a lower surface,a first end and a second end, an inner side and an outer side.Preferably, the plates are wider than the axial width of the wheel. Afirst link structure associated with the first end of the plates, and asecond link structure is associated with the second ends of the plates.Link fasteners are provided for securing the first link structures tothe second link structures of adjacent plates such that the plates forma linked circuit around the outer circumference of the wheel. A channelis formed on the lower sides of the plates. The channel is configured toreceive a portion of the outer circumference of the wheel to prevent theplates form sliding laterally from the wheel. The plates include malelink structures extending from the first ends of the plates and femalelink structures recessed within the second ends of the plates. Theplates further including inner and outer side plates depending from thelower surfaces of the plates. The inner and outer side plates line theinner and outer sides of both the male link structures and the femalelink structures. The channel formed on the lower side of the plates isdefined by the inner and outer side plates. The channel is tapered sothat the male link structures fit into the female link structures ofadjacent plates. Link pin apertures are formed within the inner andouter side plates. First pairs of link pin apertures are formed adjacentthe male link structures and second pairs of link pin apertures areformed adjacent the female link structures. The link fasteners compriselink pins inserted through the first set of link pin apertures and thesecond set of link pin apertures of adjacent plates.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a tread assembly according to anembodiment of the invention;

FIG. 2 is an illustration of a tread assembly according to the presentinvention installed on a baby stroller;

FIG. 3 is an illustration of a tread assembly according to the presentinvention installed on a wheel chair;

FIG. 4 is a top perspective view of an individual tread link accordingto an embodiment of the invention;

FIG. 5 is a bottom perspective view of the individual tread link of FIG.4;

FIG. 6 is a side view of the individual tread link of FIGS. 4 and 5;

FIG. 7 is a perspective view of a link fastener according to anembodiment of the invention;

FIG. 8 is a perspective view to two individual tread links linkedtogether according to an embodiment of the invention; and

FIG. 9 is an illustration of a tread assembly according to an embodimentof the invention installed on an adaptive stroller or pushchair intendedfor a larger child or adult with disabilities.

DETAILED DESCRIPTION

Turning to FIG. 1, the present invention relates to a removable treadassembly 100 adapted to be installed around the outer circumference of awheel 104 of a personal conveyance vehicle or other manually poweredvehicle. The tread assembly 100 is adapted to improve the performance ofthe wheel 104 when the vehicle operated over loose surfaces such as sandor snow. The removable tread assembly 100 includes a plurality ofsubstantially identical tread links 102. The tread links 102 may belinked together end-to-end in an articulating manner to form a linkagehaving a length approximately equal to the circumference of the wheel104 on which the apparatus is to be installed. The last tread link inthe assembly 102 n may be linked to the first tread link 102 a in thesame manner as the other tread links to form a linked circuit around theouter circumference of the wheel 104. The tread links 102 include arelatively flat tread plate 108 that is substantially wider than theaxial width of the wheel 104. Once installed on the wheel, the treadplates 108 present a significantly wider tread surface for engaging thesurface over which the wheel 104 is traveling. The wider tread surfaceof the tread assembly 100 prevents the wheel from sinking into loosesurfaces such as sand, snow or mud as is typically the case with therelatively narrow wheels of most personal conveyance vehicles.

Tread assemblies 100 may be installed, for example, on the rear wheels202 of a baby stroller 200 as shown in FIG. 2; the drive wheels 302 of awheel chair 300 as shown in FIG. 3; the rear wheels of an adaptivestroller or pushchair intended for a larger child or adult withdisabilities as shown in FIG. 9. Alternatively, tread assemblies 100 maybe installed on the wheels of carts or trailers or any other lightweight vehicles. Installing a tread assembly 100 to a stroller, wheelchair or other conveyance provides much greater versatility, allowingsuch conveyances to travel over surfaces such as sand, snow and mudwhich would ordinarily prove impassible.

An individual tread link 102 will now be described with reference toFIGS. 4, 5 and 6. The tread link 102 comprises a generally rectangulartread plate 108. The tread plate 108 is generally flat from side toside, and slightly from end to end. A first “male” linking structure 110extends from a first end of the tread plate 108, and a correspondingsecond “female” linking structure 118 is formed at a second end of thetread plate. The protruding first linking structure 110 of a first treadlink 35 U.S.C. § 102(a) is adapted to be inserted into the recessedsecond linking structure 118 of an adjacent tread link 102 b and securedtherein by a link fastener (described later) to form one link within theremovable link assembly 100.

An inner side plate 114 and an outer side plate 116 depend from theunderside of the tread plate 108. The inner and outer side plates extendthe length of the tread plate and line each side of the first linkingstructure 110 and the recessed sides of the second linking structure118. The inner and outer side plates 114, 116 converge toward the firstend of the tread plate 108 so that the protruding first linkingstructure 110 will fit into the recessed second linking structure of asimilarly constructed adjacent tread link 102. A profile view of theouter sidewall 118 can be seen in the side view of the tread link 102 ofFIG. 6. Though not shown, the inner sidewall 114 has a profile similarto but opposite that of the outer sidewall 116 shown in FIG. 6. First,second and third link pin apertures 120, 122, 124 are formed in theouter side plate 118. Similar first, second and third link pin apertures121, 123, and 125 are formed in the inner side plate 114 directlyopposite the first second and third outer side link pin apertures 120,122, 124 formed in the outer side plate 118. The link pin apertures 121,123, 125 formed in the inner side wall 114 and the corresponding linkpin apertures 120, 122, 124 formed in the outer side wall 116 formcooperating pairs of link pin apertures such that link pins may beinserted through corresponding sets of link pin apertures in each sideplate to link adjacent tread plates together as will be described.

The first and second pairs of link pin apertures 120, 121 and 122, 123formed in the inner and outer side plates 114, 116 are located adjacentthe recessed second linking structure 118. The third pair of linkapertures 124, 125 formed in the inner and outer side plates 114, 116are located adjacent the protruding first linking structure 110. Aconcave transverse support 132 is formed between the inner and outerside plates approximately midway between the first and second ends ofthe tread link. A similarly shaped transverse end plate 134 is formedacross the end of the protruding first linking structure 110. As bestseen in FIG. 4, the tread plate 108 extends outwardly from the outerside plate 116 much further than from the inner side plate 114. This isto present as great a surface area as possible to the ground surfacewhen the tread link is installed on a personal conveyance vehiclewithout interfering with the vehicle itself.

Turning to FIGS. 7 and 8, adjacent tread links 102 may be linkedtogether in a chain like manner. The protruding first linking structure110 of a first tread link 102 a may be inserted into the recessed secondlinking structure 118 of an adjacent tread link 102 b, such that thethird pair of link pin apertures 124, 125 formed in the inner and outerside plates 114, 116 of the first tread link 102 a adjacent theprotruding first linking structure 110 aligns with the either first orsecond pair of link pin receiving apertures 120, 121 or 122, 123 formedin the inner and outer side plates 114, 116 adjacent the recessed secondlinking structure of the second tread link 102 b. The first and secondsets of link pin receiving apertures 120, 121 and 122, 123 are providedso that the overall length of the tread assembly 100 may be adjusteddepending on whether the third pair of link pin apertures 124, 125 ofthe first tread link 102 a is aligned with the first or second set oflink pin apertures 120, 121 or 122, 123 of the second tread link 102 b.

Once the first and second tread links are properly aligned, they may besecured to one another by the link fastener 104. The link fastener 104is a U-shaped member 148 having first and second inwardly deflectingarms 150, 152. The first and second arms 150, 152 may be deflectedinwardly by simultaneously squeezing release tabs 138, 140 formed on theouter sides of each arm 150, 152. The tread links 102 and the U-shapedmember may be made of rubber, nylon ABS (acrylonitrile butadienestyrene) or ASA (acrylonitrile styrene acrylate) or other similarmaterial. The arms of the U-shaped member 150, 152 have a spring-likequality when deflected inward, such that they tend to return to theirneutral state when released. Link pins 154, 156 protrude outwardly fromthe ends of each arm 150, 152. When the third pair of link pin apertures124, 125 of the first tread link 102 a is aligned with either the firstor second pair of link pin apertures 120, 121 or 122, 123 of the secondtread link 102 b, the first and second arms of the U-shaped member 148may be deflected inward and the U-shaped member inserted into the spaceformed between the inner and outer side plates 114, 116 of the firsttread link 102 a. The link pins 154, 156 may then be aligned with thealigned link pin apertures of the first and second tread links 102 a,102 b, and the release tabs 138, 140 aligned with the release tabreceiving holes 126, 127 formed in the inner and outer side plates 114,116 of the first tread link 102 a. So aligned, the arms 150, 152 of theU-shaped may be released. Once released, the deflected arms of theU-shaped member will tend to spring outward toward their neutral,un-deflected position, forcing the locking pins 154, 156 into thealigned link pin receiving apertures of the first and second tread links102 a, 102 b. The width of the U-shaped member may be selected such thatthe width of the space between the inner and outer side plates of thetread links is somewhat narrower than the un-deflected neutral positionof the two arms 150, 152. With this arrangement the arms of the U-shapedmember will remain continuously biased against the inner and outer sideplates 114, 116, securing the link pins 154, 156 within the link pinapertures of the first and second tread links 102 a, 102 b, therebysecuring the first and second tread links 102 a, 102 b together.

When the link fastener 104 is properly seated between the inner andouter side plates 114, 116 of the first tread link 102 a, the releasetabs 138, 140 formed on the arms 150, 152 of the U-shaped member 148extend through the release tab receiving holes 126, 127 formed in theinner and outer side plates of the first tread link 102 a. The releasetabs 138, 140 may be manually pressed inward to withdraw the link pins154, 156 from the link pin apertures 120, 121 or 122, 123 of the secondtread link 102 b and the link pin receiving holds 124, 125 of the firsttread link 102 a to remove the link fastener 104 and decouple the firstand second tread links 102 a, 102 b.

In use, a plurality of tread links 102 a, 102 b, . . . , 102 n arelinked together as described. The particular number of tread linkscorresponding to the circumference the wheel on which the apparatus isto be installed. When the tread assembly is assembled, it may be wrappedaround the outer circumference of a wheel 106 as shown in FIG. 1. Thefirst and last tread links 102 a, 102 n, may then be joined and theassembly secured to the wheel 106 using a last U-shaped member asdescribed. As best seen in FIG. 5, the first and second transversesupports 132, 134 have a convex arcuate shape corresponding to thetransverse shape of the wheel or tire around which the apparatus is tobe installed. The transverse supports 132, 134 and the inner and outerside plates 114, 116 of the tread links 102 form a channel for receivingthe outer circumference of the wheel. The channel prevents the apparatusfrom sliding laterally off the sides of the wheel.

When installed on a wheel, the tread plates 108 combine to create a muchwider surface for contacting ground. The wider surface prevents thewheel from sinking into loose surfaces such as sand, mud or snow. Thewider surface allows personal conveyances such as baby strollers, wheelchairs and the like, as well as carts or other rolling devices to be farmore versatile and make many places such as beaches and snow coveredparking lots far more accessible.

Various embodiments of the invention have been described andillustrated; however, the description and illustrations are by way ofexample only. Other embodiments and implementations are possible withinthe scope of the invention and will be apparent to those of ordinaryskill in the art. Therefore, the invention is not limited to thespecific details of the representative embodiments and illustratedexamples in this description. Accordingly, the invention is not to berestricted except as necessitated by the accompanying claims and theirequivalents.

What is claimed is:
 1. A removable tread assembly adapted to beinstalled around an outer circumference of a wheel of a manually poweredvehicle, the assembly comprising: a plurality of substantially identicaltread links, the tread links including a tread plate having a firstsurface and a second surface, a first end and a second end, and thetread plate having a width greater than an axial width of the wheel, thetread links further including a first linking structure adjacent thefirst end of the tread plate and a second linking structure adjacent thesecond end of the tread plate, wherein the first linking structure of atread link is adapted to engage and be secured to the second linkingstructure of another tread link; and a plurality of substantiallyidentical link fasteners adapted to retractably engage the first andsecond linking structures of adjacent tread links to secure the adjacenttread links in an articulable manner such that the plurality of treadlinks may be linked end-to-end in a circuit around the outercircumference of the wheel.
 2. The removable tread assembly of claim 1wherein the manually operated vehicle is one of a baby stroller, babycarriage, a wheel chair, an adaptive stroller; an adaptive pushchair;and a cart.
 3. The removable tread assembly of claim 1 wherein the treadlinks further include an inner side plate and an outer side platedepending from the second surface of the tread plate, a portion of theinner and outer side plates extending beyond the first end of the treadplate, the first linking structure comprising a first pair of link pinapertures defined by the portions of the inner and outer side platesextending beyond the first end of the tread plate, and the secondlinking structure comprising a second pair of link pin apertures definedby the inner and outer side plates in an area adjacent the second end ofthe tread plate, and wherein the fasteners comprise link pins insertedinto the first and second pairs of link pin apertures of adjacent treadlinks.
 4. The removable tread assembly of claim 1 wherein the treadlinks further comprise inner and outer side plates depending from thesecond surface of the tread plate, the inner and outer side platesdefining a channel therebetween extending between the first and secondends of the tread plates.
 5. The removable tread assembly of claim 4wherein a portion of the inner and outer side plates extends beyond thefirst end of the tread plate, and wherein the inner and outer sideplates line a recess formed in the second end of the tread plate, theinner and outer side plates being spaced apart from one another in atapered manner such that the portions of the inner and outer side platesextending beyond the first end of the tread plate of the first treadlink may be inserted into the recess formed in the second end of asecond tread plate.
 6. The removable tread assembly of claim 5 whereinthe first linking structure comprises a first pair link pin aperturesdefined by the portions of the inner and outer side plates that extendbeyond the first end of the tread plate and the second linking structurecomprises a second pair of link pin apertures defined by the portions ofthe inner and outer side plates lining the recess formed in the secondend of the tread plate.
 7. The removable tread link assembly of claim 6wherein the link fasteners comprise a plurality of U-shaped membershaving first and second deflectable arms having link pins extendingoutwardly from the ends thereof, the link pins configured to be insertedthrough the first and second pairs of link pin apertures of adjacenttread links to secure the adjacent tread links in an articulatingmanner.
 8. A tread link comprising: a tread plate having first andsecond surfaces; a first linking structure associated with a first endof the tread link and a second linking structure associated with asecond end of the tread link; an inner side plate and an outer sideplate depending from the second surface of the tread plate and extendingbetween the first and second ends the tread link, the first and secondside plates spaced apart an amount sufficient to receive a portion of anouter circumference of a wheel onto which the tread link is to bemounted; and a link fastener adapted to engage the first linkingstructure associated with the first end of the tread link and a secondlinking structure associated with a second end of a similarlyconstructed tread link.
 9. The tread link of claim 8 wherein the firstlinking structure comprises a protrusion extending beyond the first endof the tread plate, and the second linking structure comprises a recessdefined by the second end of the tread plate, the protrusion configuredto fit into a corresponding recess of the similarly constructed treadlink.
 10. The tread link of claim 9 further comprising inner and outerside plates depending from the second surface of the tread plate andlining first and second sides of the protrusion as well as first andsecond sides of the recess, the inner and outer side plates defining afirst pair of link pin apertures adjacent the protrusion and a secondpair of link pin apertures adjacent the recess.
 11. The tread link ofclaim 10 further comprising a link fastener including a link pininsertable into one of the first and second pairs of link pin aperturesand the other of a first and second pair of link pin aperturesassociated with the similarly constructed tread link.
 12. The tread linkof claim 11 wherein the fastener comprises a U-shaped member havingfirst and second deflectable arms, the link pin defined by a pair ofoutwardly facing posts formed on the ends of the first and second arms.13. The tread link of claim 8 wherein the first linking structurecomprises a first hinge knuckle formed along the first end of the treadplate and the second linking structure comprises a second hinge knuckleformed along a second end of the tread plate and the fastener comprisesa hinge pin adapted to be inserted into one of the first knuckle and thesecond knuckle, and the other of a second knuckle and a first knuckleassociated with a similarly constructed tread link.
 14. An apparatus forimproving a wheel's performance on loose surfaces, the apparatuscomprising: a plurality of linked plates, the plates having an uppersurface, a lower surface, a first end and a second end, an inner sideand an outer side, the plates having a width greater than an axial widthof the wheel; first link structures associated with the first ends ofthe plates, and second link structures associated with the second endsof the plates; link fasteners for securing the first link structures tothe second link structures of adjacent plates such that the plates forma linked circuit around an outer circumference of the wheel; and achannel associated with the lower sides of the plates, the channelconfigured to receive a portion of the outer circumference of the wheel,preventing the plates form sliding laterally from the wheel.
 15. Theapparatus of claim 14 wherein the plates include male link structuresextending from the first ends of the plates and female link structuresrecessed within the second ends of the plates, the plates furtherincluding inner and outer side plates depending from the lower surfacesof the plates, the inner and outer side plates lining inner and outersides of the male link structures and the female link structures, theinner and outer side plates defining the channel, the channel beingtapered such that the male link structures fit into the female linkstructures of adjacent plates, the inner and outer side plates definingfirst sets of link pin apertures adjacent the male link structures andsecond pairs of link pin apertures adjacent the female link structures,and wherein the link fasteners comprise link pins inserted through thefirst set of link pin apertures and the second set of link pin aperturesof adjacent plates.
 16. The apparatus of claim 15 wherein the fastenerscomprise U-shaped members having first and second deflecting arms, andfirst and second link pins extending from the first and second arms. 17.The apparatus of claim 16 wherein the U-shaped members further includefirst and second release tabs formed on outer surfaces of the first andsecond arms, respectively, and wherein the inner and outer side platesdefine release tab apertures, the first and second release tabsextending through the release tab apertures when the first and secondlink pins are inserted into the first and second sets of link pinapertures of adjacent plates.
 18. The apparatus of claim 14 furthercomprising an arcuate transverse support within the channel configuredto axially engage an outer surface of the wheel.
 19. The apparatus ofclaim 14 wherein the first and second link structures comprise matinghinge knuckles formed on the first and second ends of the plates. 20.The apparatus of claim 19 wherein the fasteners comprise hinge pinsadapted to be inserted through the mating hinge knuckles associated withadjacent plates.